25 Marine Biodiversity and Ecosystem Conservation
As we have been, and will continue to learn throughout this text, there are a number of threats to marine biodiversity. These include overexploitation, invasive species, pollution, habitat degradation, ocean acidification and impacts of climate change. During the fifth International Marine Protected Areas Congress (IMPAC5) in 2022, sustainable development goal 14.5 – conserve coastal and marine areas, was accelerated to conserve 30 % of marine and coastal areas by 2030 (30 by 30; listen to podcast Protecting 30% of the World’s Land and Ocean by 2030 to learn more). There are a number of challenges and factors that need to be considered to achieve this ambitious target.
Photo © Patricia Corbett.
Sustainable Oceans
The world’s oceans are under threat from multiple unsustainable practices and disruptors. Protecting, restoring, and safeguarding these systems through global agreements and collaboration is vital to achieving a more sustainable future. Watch the video below from the Convention on Biological Diversity on ‘Sustainable Oceans: Marine Biodiversity for the Future We Want’ to learn more.
Trends in Marine Biodiversity Loss and its Consequences
Luypaert et al., (2020) grouped the threats listed by the International Union for Conservation of Nature (IUCN) into six categories (sensu Young et al. 2016): “habitat destruction and modification,” “direct exploitation,” “invasive species,” “pollution,” “climate change,” and “other.” Based on the frequency by which threatened marine species were affected by different threats, they found the most common threat to be habitat modification and destruction, followed closely by overexploitation (Figure 1a). Pollution, climate change, and invasive species were less frequently observed as threats to threatened marine species (Figure 1a).
Impact of Threats
The impact of these stressors is pervasive across the marine tree of life (Crain et al. 2009); however, as previously described for extinctions, the average number of threats affecting threatened species varies between taxonomic groups (Figure 1b). Threatened anthozoan species (sea anemones and corals) experience the highest average number of threats (Figure 1a ). Coral reefs are impacted by diverse stressors such as overfishing, coastal development, and agricultural runoff (McLeod et al. 2013). Additionally, climate change and ocean acidification are emerging stressors that have caused widespread damage to reefs around the world (Hoegh-Guldberg et al. 2007). Nearly 75% of the world’s coral reefs are affected by these stressors (Burke et al. 2011). Although threatened chondrichthyans (i.e., sharks, rays, and chimeras) are seen to have a relatively lower average number of threats, they are largely threatened by the effects of overexploitation through targeted fisheries and bycatch (Figure 1a). The unique life history characteristics of these cartilaginous fishes (late maturation, slow growth, and low reproduction rates) make them particularly vulnerable to the impact of stressors (Worm et al. 2013).
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Figure 1a.
Figure 1a is entitled ‘The distribution of anthropogenic stressors faced by marine species threatened with extinction in various marine regions of the world’. The graphic is presented as a pie chart, matching anthropogenic stressors to percentage threats and their threat designation of CR (critically endangered), EN (endangered), and VU (vulnerable), if applicable.
Climate change represents a threat of 13/8% (CR), habitat destruction and modification represents a threat of 37.2% (EN), direct exploitation represents a threat of 23.7% (VU), invasive species represents a threat of 10.5%, pollution represents a threat of 14.6%, and other represents a threat of 0.2%
Figure 1b.
Figure 1b is entitled ‘Average number of anthropogenic stressors affecting species threatened with extinction for various taxonomic groups.’ There 8 bars on the graph representing taxonomic groups and the average number of threats to their group from the set categories of ‘other’, ‘climate change’, ‘pollution’, ‘invasive species’, ‘direct exploitation’, ‘habitat destruction and modification’ and other.
The vertical axis is labelled ‘average number of threats per species’, beginning at 0 to 5.0, in increments of 0.5.
Horizontal specifies ‘taxonomic groups’, which are described below:
- Actinopterygii – includes a threat average of 0-0.1 for habitat destruction and modification, 0.1-0.5 for direct exploitation, 0.5-0.6 for invasive species, 0.6-1.0 for pollution, 1.0-1.4 for climate change and 1.4-1.45 for other
- Aves – includes a threat average of 0-0.3 for habitat destruction and modification, 0.3-1.1 for direct exploitation, 1.1-1.7 for invasive species, 1.7-2.3 for pollution, 2.3-2.7 for climate change and 2.7-2.77 for other
- Chondrichthyes – includes a threat average of 0-0.05 for habitat destruction and modification, 0.05-1.0 for direct exploitation, 1.0-1.1 for invasive species, 1.1-1.2 for pollution and 1.2-1.25 for climate change
- Mammalia – includes a threat average of 0-0.4 for habitat destruction and modification, 0.4-1.5 for direct exploitation, 1.5-1.7 for invasive species, 1.7-2.7 for pollution, 2.7-3.0 for climate change and 3.0-3.65 for other
- Reptilia – includes a threat average of 0-0.3 for habitat destruction and modification, 0.3-1.1 for direct exploitation, 1.1-1.2 for invasive species, 1.2-1.3 for pollution and 1.3-2.3 for climate change
- Anthozoa – includes a threat average of 0-1.0 for habitat destruction and modification, 1.0-2.0 for direct exploitation, 2.0-3.0 for invasive species, 3.0-4.0 for pollution, 4.0-4.9 for climate change
- Gastropoda – includes a threat average of 0-0.1 for habitat destruction and modification, 0.1-1.0 for direct exploitation, 1.0-1.05 for invasive species, 1.05-1.5 for pollution, 1.5-1.58 for climate change
- Other (composed of taxonomic groups with a low number of species threatened, including Myxini, Sarcopterygii, Polychaeta, Insecta, Malacostraca, Maxillopoda, Merostomata, Hydrozoa, and Holothuroidea) – includes a threat average of 0-0.3 for habitat destruction and modification, 0.3-1.0 for direct exploitation, 1.0-1.1 for invasive species, 1.1-1.3 for pollution, 1.3-1.5 for climate change
Figures are average numbers of stressors; all data is approximate.
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Anthropogenic Stressors
Several marine areas suffer from high human impact, particularly those where human use of the ocean is the greatest (Halpern et al. 2015). However, the distribution and impact of different anthropogenic stressors vary geographically (Figure 2). Habitat destruction and modification, and overexploitation remain the most important threats to threatened marine species across marine regions; however, their relative contribution to the overall threat level varies considerably between regions (Figure 2). Previous analyses of the cumulative anthropogenic impact on the oceans have shown that the Central and North Atlantic, the Mediterranean, the East Indian, and the Central Pacific are heavily impacted marine regions (Halpern et al. 2015). Our analysis shows that threatened species in the Atlantic and Mediterranean regions are most frequently impacted by overexploitation. Conversely, in the East Indian and Central Pacific regions, habitat modification and destruction constituted the most prevalent threat. The Arctic region is also heavily impacted anthropogenically (Halpern et al. 2015). Luypaert et al., (2020) found that threatened species in this region are heavily impacted by habitat modification and destruction, which corresponds to large-scale habitat alterations driven by changes in sea ice extent (Walsh et al. 2016). Although Antarctica has low overall anthropogenic impacts (Halpern et al. 2015), the most common threat to threatened marine species in this region is overexploitation (57%). In summary, these results indicate that anthropogenic threats to threatened marine species differ considerably between marine regions, even if the overall average number of threats may be similar (Figure 2; Halpern et al. 2015). This suggests that reducing anthropogenic impacts on threatened marine species requires targeted approaches specific to each marine region.
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Figure 2: The distribution of anthropogenic stressors faced by marine species threatened with extinction in various marine regions of the world
Figure 2 is entitled ‘The distribution of anthropogenic stressors faced by marine species threatened with extinction in various marine regions of the world’. Presented as a world map, where each marine region has a pie chart showing a percentage contribution of an anthropogenic stressors’ impact. Marine regions and their corresponding anthropogenic stressor impact includes:
- ‘Pacific north’ – habitat destruction and modification 40%, overexploitation 21%, invasive species 12%, pollution 14%, climate change 13%
- ‘Pacific central’ – habitat destruction and modification 40%, overexploitation 20%, invasive species 12%, pollution 14%, climate change 15%
- ‘Pacific south’ – habitat destruction and modification 35%, overexploitation 24%, invasive species 10%, pollution 13%, climate change 17%
- ‘Indian ocean east’ – habitat destruction and modification 41%, overexploitation 20%, invasive species 12%, pollution 14%, climate change 13%
- ‘Indian ocean west’ – habitat destruction and modification 39%, overexploitation 24%, invasive species 11%, pollution 14%, climate change 13%
- ‘Antarctic’ – habitat destruction and modification 21%, overexploitation 57%, pollution 11%, invasive species under 10 percent, climate change 11%
- ‘Atlantic south’ – habitat destruction and modification 32%, overexploitation 45%, pollution 11%, invasive species under 10 percent and climate change under 10 percent
- ‘Mediterranean and/or black sea’ – habitat destruction and modification 32%, overexploitation 48%, invasive species under 10 percent, pollution 14%, climate change under 10 percent and other under 10 percent
- ‘Atlantic central’ – habitat destruction and modification 34%, overexploitation 35%, invasive species under 10 percent, pollution 16%, climate change under 10 percent and other under 10 percent
- ‘Atlantic north’ – habitat destruction and modification 30%, overexploitation 44%, invasive species under 10 percent, pollution 11%, climate change under 10 percent and other under 10 percent
- ‘Arctic sea’ – habitat destruction and modification 45%, overexploitation 20%, invasive species under 10 percent, pollution 10%, climate change 15% and other under 10 percent
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This text and images are from “Status of Marine Biodiversity in the Anthropocene” (4.3 Trends in Marine Biodiversity Loss and its Consequences) by Thomas Luypaert, James G. Hagan, Morgan L. McCarthy & Meenakshi Poti, which is licensed under CC BY 4.0, except for the Marine Biodiversity and Ecosystem Conservation introductory paragraph, which has been added by Trish Corbett.
Further reading
Explore the paper below:
- Casey C. O’Hara and Benjamin S. Halpern (2022). Anticipating the Future of the World’s Ocean. Annual Review of Environment and Resources 47:1, 291-315. https://doi.org/10.1146/annurev-environ-120120-053645 CC BY 4.0
Activity: Test your Knowledge
Test your knowledge in the quiz below:
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Activity: Test your Knowledge
This exercise invites readers to answer questions to test their knowledge, based on the Marine Biodiversity and Ecosystem Conservation information above. Questions and answers are listed below.
Question 1
Select the top 5 contributors to marine biodiversity loss.
Select the best option from:
- habitat destruction and modification, overexploitation, invasive species, pollution, and climate change.
- habitat modification, overexploitation, invasive species, plastic pollution, and methane from farming
- habitat destruction, fisheries, plastic pollution, climate change and ocean acidification
- habitat modification, overfishing, invasive species, pollution, and climate change
Answers to question 1
- habitat destruction and modification, overexploitation, invasive species, pollution, and climate change.
Question 2
Select the two correct responses. Of the 5 top contributors to biodiversity loss, which two have caused the biggest decline in marine biodiversity? Select all that apply from:
- habitat destruction and modification
- invasive species
- climate change
- pollution
- overexploitation
Answers to question 2
- habitat destruction and modification
- overexploitation
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Activity: Marine Biodiversity and Ecosystem Conservation Word Search
Explore the Word Search activity below, using some of the keywords encountered in this chapter.
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Activity: Marine Biodiversity and Ecosystem Conservation Word Search
This exercise invites readers to search for words in a grid related to chapter content for Marine Biodiversity and Ecosystem Conservation. Words to find include: stewardship, biodiversity, conservation, inclusion, protected area, future, impetus, management, planning, EDNA, integrated, spatial, threats, impact, trends, consequences, loss, healthy, anthropogenic and stressor.
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References
Burke, L., Reytar, K., Spalding, M., & Perry, A. (2011). Reefs at risk revisited. Washington, DC: World Resources Institute (WRI).
Crain, C. M., Halpern, B. S., Beck, M. W., & Kappel, C. V. (2009). Understanding and managing human threats to the coastal marine environment. Annals of the new York Academy of Sciences, 1162(1), 39-62. https://doi.org/10.1111/j.1749-6632.2009.04496.x
Halpern, B. S., Frazier, M., Potapenko, J., Casey, K. S., Koenig, K., Longo, C., … & Walbridge, S. (2015). Spatial and temporal changes in cumulative human impacts on the world’s ocean. Nature communications, 6(1), 7615. https://doi.org/10.1038/ncomms8615
Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., … & Hatziolos, M. E. (2007). Coral reefs under rapid climate change and ocean acidification. science, 318(5857), 1737-1742. https://doi.org/10.1126/science.1152509
IUCN. (2018). The IUCN Red List of Threatened Species. Version 2018-1. http://www.iucnredlist.org
Luypaert, T., Hagan, J.G., McCarthy, M.L., Poti, M. (2020). Status of Marine Biodiversity in the Anthropocene. In: Jungblut, S., Liebich, V., Bode-Dalby, M. (eds) YOUMARES 9 – The Oceans: Our Research, Our Future. Springer, Cham. https://doi.org/10.1007/978-3-030-20389-4_4
Mcleod, E., Anthony, K. R., Andersson, A., Beeden, R., Golbuu, Y., Kleypas, J., … & Smith, J. E. (2013). Preparing to manage coral reefs for ocean acidification: lessons from coral bleaching. Frontiers in Ecology and the Environment, 11(1), 20-27. https://doi.org/10.1890/110240
Walsh, J. E., Fetterer, F., Scott Stewart, J., & Chapman, W. L. (2017). A database for depicting Arctic sea ice variations back to 1850. Geographical Review, 107(1), 89-107. https://doi.org/10.1111/j.1931-0846.2016.12195.x
Worm, B., Davis, B., Kettemer, L., Ward-Paige, C. A., Chapman, D., Heithaus, M. R., … & Gruber, S. H. (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40, 194-204. https://doi.org/10.1016/j.marpol.2012.12.034
Young, H. S., McCauley, D. J., Galetti, M., & Dirzo, R. (2016). Patterns, causes, and consequences of anthropocene defaunation. Annual review of ecology, evolution, and systematics, 47(1), 333-358. https://doi.org/10.1146/annurev-ecolsys-112414-054142
